Purpose:
In case of various neovascular eye diseases, anti-VEGF treatment has been established as the first-line therapy. However, there is a substantial number of poor-responders. Therefore, it is necessary to investigate additional targets that may be addressed by a therapy, e.g. other growth factors or cytokines besides VEGF that also may promote neovascularisation or the formation of neovascular membranes.

Methods:
Eyes of C57Bl/6J mice were treated with laser (energy 200 mW, spot diameter 50 µm) to rupture the retinal pigment epithelium (RPE) and Bruchs membrane and to elicit a neovascular and proliferative response. Eyes were isolated one, two, three and four weeks after laser treatment and embedded in paraffin. Cell populations (endothelial cells, fibroblasts, RPE, microglial cells and macrophages stained by CD31, vimentin or S100A4, RPE65 and Iba-1, respectively) present in the areas of neovascularisation in the laser spots were identified by immunohistochemistry. The proteins FGF-1, PDGF-β, TGF-β, IL-8 and IL-17 as well as their receptors were also detected in the laser spots. Levels of protein expression were quantified roughly by evaluation of digital images of stained paraffin sections.

Results:
Endothelial cells, fibroblasts, RPE cells as well as microglial cells and macrophages could be stained in the laser spot. Immunoreactivity for the investigated proteins was hardly found in the non-treated retina, but cells in the laser spot were clearly positive for these proteins, in particular PDGF-β, FGF-1 and IL-8. The same is true for the receptors of these proteins, which were clearly elevated after laser treatment. Highest values for FGF-1 and its receptor were found two weeks after laser treatment. PDGF-β, TGF-β and IL-8 levels were almost stable throughout the four weeks of observation, whereas IL-17 declined after three weeks.

Conclusions:
We could show an elevated appearance of PDGF-β, TGF-β, FGF-1, IL-17 and IL-8 as well as their receptors in laser-induced CNV. Besides VEGF, there are also other proteins that may play a role in the development and progression of choroidal neovascularisation. A time-dependent variation of protein expression was observed and might have an influence on the particular therapy response.